Bug 547003

Summary: [contentassist] NPE on 'new' assist in lambda in enum field declaration
Product: [Eclipse Project] JDT Reporter: Paul Pazderski <paul-eclipse>
Component: CoreAssignee: JDT-Core-Inbox <jdt-core-inbox>
Status: NEW --- QA Contact:
Severity: normal    
Priority: P3 CC: gayanper, stephan.herrmann
Version: 4.12   
Target Milestone: ---   
Hardware: All   
OS: All   
Whiteboard: stalebug

Description Paul Pazderski CLA 2019-05-06 07:53:00 EDT
Use the following two code files to reproduce:
=======================
public class Builder {
	public Builder set(java.util.function.Supplier<?> s) { return this; }
	public Object build() { return new Object(); }
}
=======================
public enum MyEnum {
	ENUM_VALUE(new Builder().set(() -> {
		Object o = new O
		return null;
	}).build());
	private MyEnum(Object o) {}
}
=======================

If I use content assist in the 3rd line of MyEnum (after 'new O') I get the following NPE:

The 'org.eclipse.jdt.ui.JavaAllCompletionProposalComputer' proposal computer from the 'org.eclipse.jdt.ui' plug-in did not complete normally. The extension has thrown a runtime exception.
java.lang.NullPointerException
	at org.eclipse.jdt.internal.codeassist.CompletionEngine.computeExpectedTypes(CompletionEngine.java:4030)
	at org.eclipse.jdt.internal.codeassist.CompletionEngine.complete(CompletionEngine.java:1934)
	at org.eclipse.jdt.internal.codeassist.CompletionEngine.complete(CompletionEngine.java:2271)
	at org.eclipse.jdt.internal.core.Openable.codeComplete(Openable.java:136)
	at org.eclipse.jdt.internal.core.CompilationUnit.codeComplete(CompilationUnit.java:368)
	at org.eclipse.jdt.internal.core.CompilationUnit.codeComplete(CompilationUnit.java:358)
	at org.eclipse.jdt.internal.ui.text.java.JavaCompletionProposalComputer.internalComputeCompletionProposals(JavaCompletionProposalComputer.java:253)
	at org.eclipse.jdt.internal.ui.text.java.JavaCompletionProposalComputer.computeCompletionProposals(JavaCompletionProposalComputer.java:215)
	at org.eclipse.jdt.internal.ui.text.java.JavaTypeCompletionProposalComputer.computeCompletionProposals(JavaTypeCompletionProposalComputer.java:66)
	at org.eclipse.jdt.internal.ui.text.java.CompletionProposalComputerDescriptor.computeCompletionProposals(CompletionProposalComputerDescriptor.java:336)
	at org.eclipse.jdt.internal.ui.text.java.CompletionProposalCategory.computeCompletionProposals(CompletionProposalCategory.java:340)
	at org.eclipse.jdt.internal.ui.text.java.ContentAssistProcessor.collectProposals(ContentAssistProcessor.java:334)
	at org.eclipse.jdt.internal.ui.text.java.ContentAssistProcessor.computeCompletionProposals(ContentAssistProcessor.java:291)
	at org.eclipse.jface.text.contentassist.ContentAssistant$2.lambda$0(ContentAssistant.java:2014)
	at java.util.Collections$SingletonSet.forEach(Collections.java:4767)
	at org.eclipse.jface.text.contentassist.ContentAssistant$2.run(ContentAssistant.java:2013)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:45)
	at org.eclipse.jface.text.contentassist.ContentAssistant.computeCompletionProposals(ContentAssistant.java:2010)
	at org.eclipse.jface.text.contentassist.CompletionProposalPopup.computeProposals(CompletionProposalPopup.java:575)
	at org.eclipse.jface.text.contentassist.CompletionProposalPopup.lambda$0(CompletionProposalPopup.java:505)
	at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:72)
	at org.eclipse.jface.text.contentassist.CompletionProposalPopup.showProposals(CompletionProposalPopup.java:500)
	at org.eclipse.jface.text.contentassist.ContentAssistant.showPossibleCompletions(ContentAssistant.java:1824)
	at org.eclipse.jdt.internal.ui.javaeditor.CompilationUnitEditor$AdaptedSourceViewer.doOperation(CompilationUnitEditor.java:189)
	at org.eclipse.ui.texteditor.ContentAssistAction.lambda$0(ContentAssistAction.java:85)
	at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:72)
	at org.eclipse.ui.texteditor.ContentAssistAction.run(ContentAssistAction.java:84)
	at org.eclipse.jface.action.Action.runWithEvent(Action.java:474)
	at org.eclipse.jface.commands.ActionHandler.execute(ActionHandler.java:121)
	at org.eclipse.ui.internal.handlers.E4HandlerProxy.execute(E4HandlerProxy.java:95)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.eclipse.e4.core.internal.di.MethodRequestor.execute(MethodRequestor.java:58)
	at org.eclipse.e4.core.internal.di.InjectorImpl.invokeUsingClass(InjectorImpl.java:320)
	at org.eclipse.e4.core.internal.di.InjectorImpl.invoke(InjectorImpl.java:254)
	at org.eclipse.e4.core.contexts.ContextInjectionFactory.invoke(ContextInjectionFactory.java:173)
	at org.eclipse.e4.core.commands.internal.HandlerServiceHandler.execute(HandlerServiceHandler.java:156)
	at org.eclipse.core.commands.Command.executeWithChecks(Command.java:497)
	at org.eclipse.core.commands.ParameterizedCommand.executeWithChecks(ParameterizedCommand.java:490)
	at org.eclipse.e4.core.commands.internal.HandlerServiceImpl.executeHandler(HandlerServiceImpl.java:213)
	at org.eclipse.e4.ui.bindings.keys.KeyBindingDispatcher.executeCommand(KeyBindingDispatcher.java:308)
	at org.eclipse.e4.ui.bindings.keys.KeyBindingDispatcher.press(KeyBindingDispatcher.java:584)
	at org.eclipse.e4.ui.bindings.keys.KeyBindingDispatcher.processKeyEvent(KeyBindingDispatcher.java:653)
	at org.eclipse.e4.ui.bindings.keys.KeyBindingDispatcher.filterKeySequenceBindings(KeyBindingDispatcher.java:443)
	at org.eclipse.e4.ui.bindings.keys.KeyBindingDispatcher.access$2(KeyBindingDispatcher.java:386)
	at org.eclipse.e4.ui.bindings.keys.KeyBindingDispatcher$KeyDownFilter.handleEvent(KeyBindingDispatcher.java:96)
	at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:89)
	at org.eclipse.swt.widgets.Display.filterEvent(Display.java:1194)
	at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1055)
	at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1080)
	at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1065)
	at org.eclipse.swt.widgets.Widget.sendKeyEvent(Widget.java:1107)
	at org.eclipse.swt.widgets.Widget.sendKeyEvent(Widget.java:1103)
	at org.eclipse.swt.widgets.Widget.wmChar(Widget.java:1490)
	at org.eclipse.swt.widgets.Control.WM_CHAR(Control.java:4884)
	at org.eclipse.swt.widgets.Canvas.WM_CHAR(Canvas.java:353)
	at org.eclipse.swt.widgets.Control.windowProc(Control.java:4764)
	at org.eclipse.swt.widgets.Canvas.windowProc(Canvas.java:348)
	at org.eclipse.swt.widgets.Display.windowProc(Display.java:4770)
	at org.eclipse.swt.internal.win32.OS.DispatchMessage(Native Method)
	at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3545)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$5.run(PartRenderingEngine.java:1173)
	at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:338)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:1062)
	at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:155)
	at org.eclipse.ui.internal.Workbench.lambda$3(Workbench.java:631)
	at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:338)
	at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:555)
	at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:150)
	at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:155)
	at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:203)
	at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:137)
	at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:107)
	at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:400)
	at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:255)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:661)
	at org.eclipse.equinox.launcher.Main.basicRun(Main.java:597)
	at org.eclipse.equinox.launcher.Main.run(Main.java:1476)
	at org.eclipse.equinox.launcher.Main.main(Main.java:1449)
Comment 1 Eclipse Genie CLA 2021-04-26 17:59:22 EDT
This bug hasn't had any activity in quite some time. Maybe the problem got resolved, was a duplicate of something else, or became less pressing for some reason - or maybe it's still relevant but just hasn't been looked at yet.

If you have further information on the current state of the bug, please add it. The information can be, for example, that the problem still occurs, that you still want the feature, that more information is needed, or that the bug is (for whatever reason) no longer relevant.

--
The automated Eclipse Genie.
Comment 2 Stephan Herrmann CLA 2021-05-22 17:11:20 EDT
still happens on HEAD
Comment 3 Stephan Herrmann CLA 2021-05-22 17:22:04 EDT
NPE happens at this line

		TypeBinding binding = variable.type.resolvedType;

variable is the FieldDeclaration "ENUM_VALUE". NPE is no surprise: enum constants are represented by a FieldDeclaration without a .type (because the type is implicitly given as the enclosing enum).

fix would be along the lines of

		TypeBinding binding = ((FieldDeclaration)variable).binding.type;

(but that cast is not good of course).

Why don't we have "VariableBinding AbstractVariableDeclaration.getVariableBinding()" ? Ups, because TypeParameter extends AbstractVariableDeclaration, and it doesn't have a VariableBinding. Outch.
Comment 4 Eclipse Genie CLA 2023-06-04 09:56:36 EDT
This bug hasn't had any activity in quite some time. Maybe the problem got resolved, was a duplicate of something else, or became less pressing for some reason - or maybe it's still relevant but just hasn't been looked at yet.

If you have further information on the current state of the bug, please add it. The information can be, for example, that the problem still occurs, that you still want the feature, that more information is needed, or that the bug is (for whatever reason) no longer relevant.

--
The automated Eclipse Genie.